The present invention relates to an automatic loading camera capable of automatically loading 35-mm film (J135 roll film).
An automatic loading camera employs two types of film feeding systems. One system is a sprocket driving system in which a sprocket gear meshing with perforations of a film is driven to feed the film toward a spool mounted in a camera so that the film is wound on the spool. The other is a spool driving system in which a spool is driven to wind the film at the same time the film is fed.
In the sprocket driving system, a spool must wind a film at a speed corresponding to the feed speed of the film fed by a sprocket gear. Therefore, in order to respond to an increase in winding diameter, a known slipping mechanism utilizing friction must be located between the spool and a spool shaft, resulting in a complicated mechanism. In addition, since a large rotating force must be transmitted to the spool shaft to overcome the friction, a power loss is increased.
On the contrary, the spool driving system does not require the above slipping mechanism nor a sprocket driving mechanism. Therefore, a structure of the system is simplified, and a rotating force to be transmitted to the spool can be relatively small. For this reason, the spool driving system is suitable for a small and inexpensive compact camera.
Systems for winding a film on a spool can be classified into two classes: a friction system for winding a film by utilizing a frictional force; and a claw system in which a claw is formed on a spool and meshes with a perforation of a film. In the friction system, since an urging member having a large urging force is required to satisfactorily utilize a frictional force between a film and a spool, a power loss is larger than that in the claw system. Therefore, the claw winding system is generally used in combination with a spool driving system. A combination of the two systems will be referred to as a spool driving system hereinafter.
In the claw-type spool driving system, however, a perforation of a film leader portion must be engaged with and fixed to a claw formed on a spool circumferential surface. Precision of such a film loading operation depends on an operator's skill. Therefore, film winding is sometimes started while the film leader portion is incompletely fixed.
Even when a film is completely engaged with the claw, a film leader portion floating from the spool circumferential surface is pushed by the surface of the film to be subsequently wound for a second turn when the spool rotates once. As a result, the perforation is easily disengaged from the claw.
Even when the claw is not disengaged from the perforation, the film floats from the spool circumferential surface to cause a so-called loose winding state. As a result, the film extends in a film winding chamber and rubs against wall surfaces of the chamber, thereby disabling film winding.